Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
  • G11B7/244—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only
  • G11B7/246—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only containing dyes
  • G11B7/248—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only containing dyes porphines; azaporphines, e.g. phthalocyanines
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/146—Laser beam

Definitions

• the present invention relates to an optical information recording method, in which information is recorded and played back with a laser, and to an optical information recording medium used in the method.
• the invention relates to a heat-mode optical information recording medium on which information is recorded by irradiating the medium with a shortwave laser having a wavelength of 450 nm or shorter, and to an optical information recording method using the medium.
• a CD-R is a writable, optical information recording medium (optical disc) on which information can be written only once by irradiation with a laser, and has conventionally been known.
• a CD-R typically comprises a transparent disc substrate having successively disposed thereon a recording layer including an organic dye, a reflective layer including metal such as gold, and a protective layer made of resin.
• Information is recorded on the CD-R by irradiating the disc with a near infrared laser (i.e., a laser generally having a wavelength of around 780 nm). Specifically, the portion of the dye recording layer that is irradiated absorbs light, whereby temperature increases at the irradiated portion.
• a near infrared laser i.e., a laser generally having a wavelength of around 780 nm
• the increase in temperature produces a physical or chemical change (e.g., formation of pits) to thereby alter the optical characteristics of the irradiated portion, whereby information is recorded.
• the information thus recorded on the optical disc is ordinarily read (played back) by irradiating the optical disc with a laser having the same wavelength as that of the laser used to record the information and detecting a difference in reflectance between the region of the dye recording layer whose optical characteristics have been changed (recorded portion) and the region of the dye recording layer whose optical characteristics have not been changed (unrecorded portion).
• DVD-Rs digital versatile disc-recordable discs
• a transparent disc substrate disposed with a guide groove (pre-groove) for tracking irradiated laser light and having a width that is equal to or less than half (0.74 to 0.8 ⁇ m) the width of the pre-groove of a CD-R.
• DVD-Rs typically comprise two such transparent disc substrates that each have successively disposed thereon a dye recording layer, a reflective layer, and, if needed, a resin protective layer, with the discs being adhered together so that the recording layers face inward.
• DVD-Rs may also comprise one such transparent disc substrate (disposed with the aforementioned layers) adhered together with a protective substrate having the same disc shape as the transparent disc substrate, with the recording layer similarly facing inward.
• Information is recorded onto or played back from the DVD-R by irradiating the DVD-R with a visible laser (ordinarily having a wavelength of 630 nm to 680 nm), and it is possible to record at a higher density than a CD-R.
• 4-74690, 7-304256, 7-304257, 8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207, 2000-43423, 2000-108513, 2000-113504, 2000-149320, 2000-158818, and 2000-228028 disclose methods for recording information on and playing back information from optical recording media including an organic dye recording layer by irradiating the recording layer with a laser having a wavelength of 530 nm or less.
• optical discs including a recording layer comprising a dye such as a porphyrin compound, an azo dye, a metallic azo dye, a quinophthalone dye, a trimethynecyanine dye, a dicyanovinylphenyl skeleton dye, a coumalin compound, and a naphthalocyanine compound.
• a dye such as a porphyrin compound, an azo dye, a metallic azo dye, a quinophthalone dye, a trimethynecyanine dye, a dicyanovinylphenyl skeleton dye, a coumalin compound, and a naphthalocyanine compound.
• optical information recording media with which it is possible to record and play back information using lasers in mutually different wavelength regions have been proposed.
• JP-A Nos. 2000-141900, 2000-158816, 2000-185471, 2000-289342, and 2000-309165 propose recording media with which it is possible to record and play back information with any laser by mixing dyes used in CD Rs and dyes used in DVD-Rs together.
• the present inventors have ascertained that further improvement is needed because, when information is recorded on the above-described conventional optical discs by irradiating the discs with a shortwave laser having a wavelength of 450 nm or less, recording characteristics, such as reflectance and percentage modulation, are not satisfactory and storage stability is insufficient.
• recording characteristics of the above-described optical discs drop when the discs are irradiated with a laser having a wavelength in the vicinity of 405 nm.
• the present invention was devised to eliminate the above-described problems in the prior art.
• a first aspect of the invention is a method of recording information on an optical information recording medium by irradiating the medium with a laser having a wavelength no greater than 450 nm, wherein a recording layer of the optical information recording medium contains a phthalocyanine derivative.
• a second aspect of the invention is an optical information recording medium that is used in the optical information recording method.
• a third aspect of the invention is an optical information recording medium used in a method of recording information by irradiating the medium with a laser having a wavelength no greater than 450 nm, wherein a recording layer of the optical information recording medium contains a phthalocyanine derivative having a substituent at an ⁇ -position thereof.
• the phthalocyanine derivative has a main absorption band of around 700 nm and a sub-absorption band of around 340 nm.
• R ⁇ 1 to R ⁇ 8 and R ⁇ 1 to R ⁇ 8 each independently represents one selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a formyl group, a carboxyl group, a sulfo group, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 15 carbon atoms, a heterocyclic group having 1 to 10 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, an acyl group having 2 to 21 carbon atoms, an alkylsulfonyl group having 1 to 20 carbon atoms, an arylsulfonyl group having 6 to 14 carbon atoms, an aralkyl
• the optical information recording medium of the present invention also preferably includes a reflective layer of metal disposed on the recording layer, and more preferably also includes a protective layer disposed on the recording layer.
• a pre-groove having a track pitch of 0.2 to 0.5 ⁇ m is formed on the surface of the substrate disposed with the recording layer.
• the optical information recording method of the invention records information on the optical information recording medium by irradiating the medium with a laser having a wavelength of 450 nm or less or a laser light having a wavelength of 750 to 850 nm. Since the recording layer of the medium includes the phthalocyanine derivative having a main absorption band of around 700 nm and a sub-absorption band of around 340 nm, information can be recorded by selectively irradiating either the laser light having a wavelength of 450 nm or less or the laser light having a wavelength of 750 to 850 nm.
• a light beam for recording (e.g., a semiconductor laser) is irradiated onto an optical information recording medium disposed with a recording layer while the medium is rotated at a constant linear velocity (in the case of a CD, at 1.2 to 1.4 m/sec) or at a constant angular velocity.
• the recording layer absorbs the light, which produces a local increase in temperature, whereby optical characteristics of the recording layer change as a result of physical or chemical changes (e.g., formation of pits) and information is recorded.
• a semiconductor laser light having an oscillation wavelength ranging from 390 to 450 nm is used as the recording light.
• Examples of preferable light sources include a bluish-purple semiconductor laser having an oscillation wavelength ranging from 390 to 415 nm and a bluish-purple SHG laser having a central oscillation wavelength of 405 to 425 nm obtained by halving the wavelength of an infrared semiconductor laser, whose central oscillation wavelength is 850 nm, using a optical waveguide element.
• the bluish-purple semiconductor laser is particularly preferable in terms of recording density. Recorded information can be played back by irradiating the medium with the semiconductor laser while rotating the medium at the same constant linear velocity as mentioned above and detecting the reflected light.
• the medium includes a recording layer that contains a phthalocyanine derivative.
• the phthalocyanine derivative has a main absorption band of around 700 nm and a sub-absorption band of around 340 nm.
• the phthalocyanine derivative as recording material of the recording layer, it is possible to obtain an optical information recording medium that has excellent recording/playback characteristics and has high reflectance and high percentage modulation even with respect to a shortwave laser having a wavelength of 450 nm or less.
• the medium also has good recording/playback characteristics and high reflectance and high percentage modulation even with respect to a laser having wavelength of 750 to 850 nm.
• the phthalocyanine derivative has a specific substituent, the phthalocyanine derivative forms an amorphous phase that is stable thermodynamically. Therefore, there is no occurrence of phase transition, such as crystallization of the recording layer, when the medium is stored. Accordingly, the present invention has excellent storage stability.
• the phthalocyanine derivative used in the medium of the invention is preferably a compound represented by the following general formula (I).
• R ⁇ 1 to R ⁇ 8 and R ⁇ 1 to R ⁇ 8 each independently represents one selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a formyl group, a carboxyl group, a sulfo group, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 15 carbon atoms, a heterocyclic group having 1 to 10 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, an acyl group having 2 to 21 carbon atoms, an alkylsulfonyl group having 1 to 20 carbon atoms, an arylsulfonyl group having 6 to 14 carbon atoms, an
• all of R ⁇ 1 to R ⁇ 8 are preferably not simultaneously hydrogen atoms; further, at least four of the substituents, namely, R ⁇ 1 or R ⁇ 2 , R ⁇ 3 or R ⁇ 4 , R ⁇ 5 or R ⁇ 6 , and R ⁇ 7 or R ⁇ 8 , are preferably not simultaneously hydrogen atoms. And all of R ⁇ 1 to R ⁇ 8 in the general formula (I) are preferably simultaneously hydrogen atoms.
• R ⁇ 1 to R ⁇ 8 and R ⁇ 1 to R ⁇ 8 are a hydrogen atom, a halogen atom, a carboxyl group, a sulfo group, an alkyl group having 1 to 16 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 16 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an alkylsulfonyl group having 1 to 16 carbon atoms, an arylsulfonyl group having 6 to 14 carbon atoms, an aralkylsulfonyl group having 7 to 15 carbon atoms, a heterylsulfonyl group having 1 to 8 carbon atoms, a sulfamoyl group having 2 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 17 carbon atoms, an aryloxycarbonyl group having 7 to 11 carbon atom
• More preferable examples are a hydrogen atom, a halogen atom, a carboxyl group, a sulfo group, an alkoxy group having 1 to 16 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an alkylsulfonyl group having 1 to 14 carbon atoms, an arylsulfonyl group having 6 to 10 carbon atoms, an aralkylsulfonyl group having 7 to 11 carbon atoms, a heterylsulfonyl group having 1 to 8 carbon atoms, a sulfamoyl group having 2 to 16 carbon atoms, an alkoxycarbonyl group having 2 to 13 carbon atoms, an acylamino group having 2 to 14 carbon atoms, and a sulfonylamino group having 1 to 14 carbon atoms.
• R ⁇ 1 to R ⁇ 8 are a hydrogen atom, a halogen atom, a sulfo group, an alkoxy group having 8 to 16 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, an arylsulfonyl group having 6 to 10 carbon atoms, an aralkylsulfonyl group having 7 to 11 carbon atoms, a sulfamoyl group having 1 to 12 carbon atoms, an acylamino group having 2 to 12 carbon atoms, or a sulfonylamino group having 1 to 12 carbon atoms.
• R ⁇ 1 to R ⁇ 8 are a hydrogen atom and a halogen atom.
• R ⁇ 1 to R ⁇ 8 are a sulfo group, an alkylsulfonyl group having 1 to 10 carbon atoms, a phenylsulfonyl group, a benzylsulfonyl group or a sulfamoyl group having 1 to 10 carbon atoms, with R ⁇ 1 to R ⁇ 8 being a hydrogen atom.
• R ⁇ 1 to R ⁇ 8 and R ⁇ 1 to R ⁇ 8 each may have a substituent.
• the substituent include a chain or cyclic alkyl group having 1 to 20 carbon atoms (for example, a methyl group, an ethyl group, an isopropyl group or a cyclohexyl group), an aryl group having 6 to 18 carbon atoms (for example, a phenyl group, a chlorophenyl group, a 2,4-di-t-amylphenyl group, or a 1-naphthyl group), an aralkyl group having 7 to 18 carbon atoms (for example, a benzyl group or an anisyl group), an alkenyl group having 2 to 20 carbon atoms (for example, a vinyl group or a 2-methylvinyl group), an alkynyl group having 2 to 20 carbon atoms (for example, an ethynyl group,
• preferable examples of the substituent in R ⁇ 1 to R ⁇ 8 and R ⁇ 1 to R ⁇ 8 are a chain or cyclic alkyl group having 1 to 16 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 15 carbon atoms, an alkoxy group having 1 to 16 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, a halogen atom, an alkoxycarbonyl group having 2 to 17 carbon atoms, a carbamoyl group having 1 to 10 carbon atoms, and an amide group having 1 to 10 carbon atoms.
• More preferable examples are a chain or cyclic alkyl group having 1 to 10 carbon atoms, an aralkyl group having 7 to 13 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, chlorine atom, an alkoxycarbonyl group having 2 to 11 carbon atoms, a carbamoyl group having 1 to 7 carbon atoms, and an amide group having 1 to 8 carbon atoms.
• Particularly preferable examples are a branched chain or cyclic alkyl group having 1 to 8 carbon atoms, an aralkyl group having 7 to 11 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkoxycarbonyl group having 3 to 9 carbon atoms, a phenyl group, and a chlorine atom.
• the most preferable example is an alkoxy group having 1 to 6 carbon atoms.
• M is preferably metal, more preferably zinc, magnesium, copper, nickel, or palladium, even more preferably copper or nickel, and most preferably copper.
• the molecular weight of the compound represented by general formula (I) is preferably 1300 or less, and more preferably 1200 or less. Further, it is particularly preferable that the substituent represented by R ⁇ 1 , R ⁇ 2 , R ⁇ 3 , R ⁇ 4 , R ⁇ 5 , R ⁇ 6 , R ⁇ 7 , or R ⁇ 8 is a sulfamoyl group, an alkylsulfonyl group, arylsulfonyl group or an aralkylsulfonyl group.
• R ⁇ 1 or R ⁇ 2 , R ⁇ 3 or R ⁇ 4 , R ⁇ 5 or R ⁇ 6 , and R ⁇ 7 or R ⁇ 8 are preferably the same alkylsulfonyl groups or the same arylsulfonyl groups.
• each unit may be the same or mutually different, or may bond to a polymer chain such as polystyrene, polymethacrylate, polyvinyl alcohol, or cellulose.
• the phthalocyanine derivative represented by general formula (I) and used in the medium of the invention may be a specific derivative used singly or a mixture of several derivatives having different structures. In order to prevent crystallization of the recording layer, it is preferable to use a mixture of isomers whose substituents have different substitution positions.
• the recording layer of the medium absorbs energy of the laser used in recording and undergoes chemical or physical decomposition, whereby recording marks (pits) are formed in the recording layer.
• the pits are detected by differences in reflectance at the time of playback.
• An extinction coefficient (k) is an optical property relating to the amount of light energy absorbed. It is not only associated with the amount of energy of the laser light absorbed during recording by the recording layer, but is also concerned with reflectance detected at the time of recording/playback.
• a refractive index (n) relates to optical magnitude (the amount of change in reflection characteristics) of the recording marks.
• the output of the laser light used for recording actually ranges from several mW to tens of mW, preferable ranges of the extinction coefficient (k) and refractive index (n) exist in correspondence to the basic skeleton of the compounds used in the recording layer.
• the refractive index (n) and extinction coefficient (k) of the recording layer containing the compounds represented by general formula (I) are preferably respectively in a range of 1.0 ⁇ n ⁇ 1.9 and in a range of 0.03 ⁇ k ⁇ 0. 30 with respect to the wavelength of the laser used for recording, and more preferably respectively in a range of 1.5 ⁇ n ⁇ 1.9 and in a range of 0.04 ⁇ k ⁇ 0.15.
• the refractive index (n) and the extinction coefficient (k) can easily be measured by ellipsometry.
• R x / R y (each of x and y represents either one of ⁇ 1 to ⁇ 8 or ⁇ 1 to ⁇ 8) means either one of R x or R y . Accordingly, compounds indicated thereby are mixtures of substitution position isomers. In the case of unsubstituted compounds, i.e. the compounds substitute hydrogen atoms, the representation is omitted. No.
• the phthalocyanine derivative used in the present invention can be synthesized by the methods described in Putaroshianin: Kagaku to kinô ("Phthalocyanines: Chemistry and Function"), ed. by H. Shirai and N. Kobayashi (Tokyo: IPC Co., Ltd., 1997), pp. 1-62, and in Phthalocyanines: Properties and Applications, ed. by C. C. Leznoff and A. B. P. Lever (VCH Publishers: New York, 1989, 1993), pp. 1-54, or by a similar method.
• the medium of the invention comprises a substrate having disposed thereon a recording layer containing the above-mentioned phthalocyanine derivative.
• the content of the phthalocyanine derivative is preferably 80% by weight or more, and more preferably 90% by weight or more, in the recording layer. If the content is less than 80% by weight, the refractive index with respect to the laser light decreases, and as a result the percentage modulation may decrease.
• the medium of the invention may preferably comprise a disc substrate having successively disposed thereon the recording layer, a reflective layer, and a protective layer, with a pre-groove having a fixed track pitch being formed in the substrate.
• the medium may also preferably comprise a disc substrate having successively disposed thereon the reflective layer, a recording layer, and a protective layer.
• the medium may also preferably comprise two transparent disc substrates, each of which includes a pre-groove having a fixed track pitch and is disposed with the recording layer and a reflective layer, adhered together so that the recording layers face inward.
• the medium comprises a disc substrate having successively disposed thereon the recording layer, a reflective layer, and a protective layer.
• the medium will be described in accordance with the process by which it is manufactured.
• the medium of the invention may be formed in a manner similar to a conventional DVD-R, in which two transparent disc substrates, each of which includes a pre-groove having a fixed track pitch and is disposed with the recording layer and a reflective layer, are adhered together so that the recording layers face inward.
• the medium of the invention may also be formed by this layered product being adhered to a disc-shaped protective substrate having the same configuration as the layered product, with the recording layer facing inward.
• the transparent substrate has a diameter of 120 ⁇ 3 mm and a thickness of 0.6 ⁇ 0.1 mm, with the thickness of the medium after bonding being adjusted to 1.2 ⁇ 0.2 mm.
• the substrates may be bonded with a UV-curable resin used to form the protective layer or with a synthetic binder.
• a double-coated tape may be also used.
• the medium of the invention may comprise a disc substrate that includes a pre-groove having a fixed track pitch and is successively disposed with a reflective layer, a recording layer, and a thin film protective layer.
• the thin film protective layer is disposed on an opposite side of the substrate, which has a predetermined thickness (in the case of a CD-R, 1.2 mm).
• the medium is recorded by irradiating a light from the side of the substrate disposed with the thin film protective layer, whereby the beam diameter of the irradiated laser can be made smaller and it is possible to effect high density recording with light having a short wavelength of 450 nm or less.
• the thin-film protective layer preferably has a thickness of 0.1 to 300 ⁇ m, and is made of a photoresist or a filmlike resin. It should be noted that the thin film protective layer may be disposed on the recording layer via an intermediate layer or an adhesive layer.
• the intermediate layer is disposed to enhance preservability of the recording layer and to enhance adhesion between the recording layer and the thin-film protective layer. Examples of material used for the intermediate layer include inorganic materials such as ZnS-SiO 2 , ZnS, SiO, SiO 2 , MgF 2 , SnO 2 , or Si 3 N 4 .
• the intermediate layer can be formed by vacuum formation, such as deposition or sputtering.
• the adhesive layer it is preferable to use an adhesive containing a photoresist.
• the photoresist can be used as it is or be dissolved into a solvent to make a coating solution.
• the solution is coated onto the intermediate layer to make a coating film, and then a resin film obtained by extruding plastic is laminated on the coating film. Light is irradiated onto the laminated resin film, whereby the coating film is cured and the resin film is adhered onto the intermediate layer to form the thin film protective layer.
• the medium of the invention it is possible to use a substrate that includes a pre-groove whose track pitch is narrower than that of a CD-R or DVD-R in order to achieve even higher recording density.
• the track pitch is preferably 0.2 to 0.8 ⁇ m, more preferably 0.2 to 0.5 ⁇ m, and most preferably 0.2 to 0.4 ⁇ m.
• the depth of the pre-groove is preferably 0.01 to 0.18 ⁇ m and more preferably 0.02 to 0.15 ⁇ m.
• Materials for the substrate can be arbitrarily selected from various kinds of materials that are used as for substrates in conventional optical information recording media. Examples thereof include glass, polycarbonate, acrylic resins such as polymethyl methacrylate, polyvinylchloride resins such as polyvinyl chloride and vinylchloride copolymer, epoxy resin, amorphous polyolefin, and polyester. If necessary, these materials may be used in combination. These materials can be used in the form of a film or a substrate that has rigidity. Polycarbonate is preferable in view of resistance to moisture, dimensional stability, and cost.
• An undercoat layer may be provided on the surface of the substrate on which the recording layer is disposed in order to improve flatness, enhance adhesive force, and prevent degeneration of the recording layer.
• materials for the undercoat layer include: polymeric substances, such as polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, styrene/maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide, styrene/vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinylacetate/vinylchloride copolymer, ethylene/vinylacetate copolymer, polyethylene, polypropylene, and polycarbonate; and surface modifiers, such as a silane coupling agent.
• the undercoat layer can be formed by dissolving or dispersing the above-mentioned material into a suitable solvent to prepare a coating solution, and then spin-coating, dip-coating, or extrusion-coating the solution onto the surface of the substrate.
• the thickness of the undercoat layer is generally 0.005 to 20 ⁇ m and preferably 0.01 to 10 ⁇ m.
• the recording layer can be formed by deposition, sputtering, CVD, or coating a solvent, but coating a solvent is preferable.
• a coating solution is prepared by dissolving the above-mentioned dye compound and, if necessary, a quencher, a binder and the like, in a solvent. The solution is then coated onto the surface of the substrate and dried to form a coating film.
• Examples of the solvent for the coating solution include: esters, such as butyl acetate, ethyl lactate, and cellosolve acetate; ketones, such as methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; chlorinated hydrocarbons, such as dichloroethane, 1,2-dichloroethane, and chloroform; amides, such as dimethylformamide; hydrocarbons, such as methyl cyclohexane; ethers, such as dibutyl ether, diethyl ether, tetrahydrofuran, and dioxane; alcohols, such as ethanol, n-propanol, isopropanol, n-butanol, and diacetone alcohol; fluorine solvents, such as 2,2,3,3-tetrafluoropropanol; and glycolethers, such as ethylene glycol monomethyl ether, ethylene glycol monoeth
• solvents can be used singly or in combination of two or more, with consideration given to the solubility of the dye used.
• Various additives can also be added to the coating solution as needed, such as antioxidants, UV absorbents, plasticizers, and lubricants.
• examples thereof can include: natural organic polymeric substances, such as gelatin, cellulose derivatives, dextran, rosin, or rubber; and synthetic organic polymeric substances, such as hydrocarbon resins like polyethylene, polypropylene, polystyrene, and polyisobutylene, vinyl resins like polyvinyl chloride, polyvinylidene chloride, and polyvinyl chloride/polyvinyl acetate copolymer, acrylic resins like polymethyl acrylate and methyl polymethacrylate, and initial condensation products of thermosetting resins like polyvinyl alcohol, chlorinated polyethylene, epoxy resin, butyral resin, rubber derivative, and phenol/formaldehyde resin.
• natural organic polymeric substances such as gelatin, cellulose derivatives, dextran, rosin, or rubber
• synthetic organic polymeric substances such as hydrocarbon resins like polyethylene, polypropylene, polystyrene, and polyisobutylene, vinyl resins like polyvinyl chloride, polyvinylidene
• the amount of the binder is generally 0.01 to 50 times (weight ratio), and preferably 0.1 to 5 times (weight ratio), the amount of the dye (phthalocyanine derivative).
• the concentration of the dye in the coating solution is generally 0.01 to 10% by weight and preferably 0.1 to 5% by weight.
• the solvent can be sprayed, spin-coated, dipped, roll-coated, blade-coated, doctor-rolled, or screen-printed onto the substrate.
• the recording layer may comprise a single or multiple layers.
• the thickness of the recording layer is generally 10 to 500 nm, preferably 15 to 300 nm, and more preferably 20 to 100 nm.
• the recording layer can contain various discoloration inhibitors in order to enhance light resistance of the recording layer.
• a singlet oxygen quencher is used as the discoloration inhibitor.
• the singlet oxygen quencher include those described in patent publications such as JP-A Nos. 58-175693, 59-81194, 60-18387, 60-19586, 60-19587, 60-35054, 60-36190, 60-36191, 60-44554, 60-44555, 60-44389, 60-44390, 60-54892, 60-47069, 63-209995, and 4-25492, Japanese Patent Application Publication Nos. 1-38680 and 6-26028, German Patent No 350399, and in other publications such as Nihon kagakukaishi , Oct. 1992, pp. 1141.
• Other preferable examples of the singlet oxygen quencher include the compounds represented by the following general formula (II). wherein R 21 represents an alkyl group that may have a substituent and Q - represents an anion.
• R 21 is generally an alkyl group having 1 to 8 carbon atoms and may have a substituent, and preferably an unsubstituted alkyl group having 1 to 6 carbon atoms.
• substituent for the alkyl group include a halogen atom (for example, F and Cl), an alkoxy group (for example, methoxy and ethoxy), an alkylthio group (for example, methylthio and ethylthio), an acyl group (for example, acetyl and propyonyl), an acyloxy group (for example, acetoxy and propionyloxy), a hydroxy group, an alkoxy carbonyl group (for example, methoxy carbonyl and ethoxycarbonyl), an alkenyl group (for example, vinyl), and an aryl group (for example, phenyl and naphthyl).
• a halogen atom for example, F and Cl
• an alkoxy group for example, methoxy and
• a halogen atom, an alkoxy group, an alkylthio group, and an alkoxy carbonyl group are preferable.
• Preferable examples of the Q - anion include ClO 4 - , AsF 6 - , BF 4 - , and SbF 6 - .
• the amount of the discoloration inhibitor is generally 0.1 to 50% by weight, preferably 0.5 to 45% by weight, even more preferably 3 to 40% by weight, and most preferably 5 to 25% by weight with respect to the dye (the phthalocyanine derivative).
• the substance of the reflective layer has a high reflectance with respect to the laser, and examples thereof include metals, such as Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, and Bi, metalloids and stainless steel. These materials may be used singly, in combination of two or more, or as alloys.
• the reflective layer can be formed on the substrate or recording layer by deposition, sputtering, or ion-plating of the light reflective material.
• the thickness of the reflective layer is generally 10 to 300 nm and preferably 50 to 200 nm.
• a protective layer on the reflective layer or the recording layer in order to physically and chemically protect the recording layer.
• the medium of the invention comprises a DVD-R structure (i.e., when two substrates are bonded together with the recording layers facing inward)
• the material used for the protective layer include inorganic materials, such as ZnS-SiO 2 , ZnS, SiO, SiO 2 , MgF 2 , SnO 2 , and Si 3 N 4 , and organic materials, such as thermoplastic resins, thermosetting resins, and UV-curable resins.
• the protective layer can be formed by laminating a film obtained by extruding plastic on the reflection layer via an adhesive.
• the protective layer can be vacuum-deposited, sputtered, or coated.
• the protective layer comprises a thermoplastic resin or a thermosetting resin
• the protective layer can be formed by dissolving the resin into a solvent to prepare a coating solution, coating the solution, and allowing it to dry.
• the protective layer comprises a UV-curable resin
• the UV-curable resin can be using as it is or dissolved in a solvent to prepare a coating solution. In the latter case, the solution is coated and then irradiated with ultraviolet light to cure the resin.
• Various additives may be further added to these solutions as needed, such as antistatic agents, antioxidants, and UV absorbents.
• the thickness of the protective layer is generally 0.1 ⁇ m to 1 mm.
• a laminated product comprising either a substrate having successively formed thereon a recording layer, a reflective layer, and a protective layer, or a substrate having successively disposed thereon a reflective layer, a recording layer, and a protective layer, is formed.
• a compound (I-1) was dissolved into 2, 2, 3, 3-tetrafluoropropanol to obtain a coating solution for forming a recording layer (concentration: 1% by weight).
• the coating solution was spin-coated onto the surface of a polycarbonate substrate (diameter: 120 nm; thickness: 0.6 mm) disposed with a spiral pre-groove (track pitch: 0.4 ⁇ m; groove width: 0.2 ⁇ m; groove depth: 0.08 ⁇ m) formed by injection molding, whereby the recording layer was formed (thickness (inside pre-groove): approximately 80 nm).
• Optical discs of the invention were formed in the same manner as in Example 1, except that compound (I-1) was changed to compounds shown in Table 6 (amount not changed).
• Comparative optical discs were manufactured in the same manner as in Example 1, except that compound (I-1) was changed to comparative dye compounds A to G (amount not changed) shown below.
• a 14T-EFM signal was recorded using a bluish-purple semiconductor laser whose oscillation wavelength was 405 nm, at a linear velocity of 3.5 m/sec, onto each of the optical discs prepared in Examples 1 to 17 and Comparative Examples 1 to 7, and then the recorded signal was played back. Percentage modulation, C/N (Carrier/Noise Ratio) and groove reflectance were measured at an optimum power. The optical discs were then left for 100 days under forced conditions of a temperature of 80°C and a humidity of 85%, and thereafter percentage modulation was measured to evaluate deterioration of the recorded signal. Evaluation of recording and recording characteristics was performed using a DDU1000 manufactured by Pulstec Industrial Co., Ltd. The results of the evaluation are shown in Table 5.
• optical discs of the invention (Examples 1 to 17) disposed with the recording layer containing the phthalocyanine derivative, when compared to the comparative optical discs (Comparative Examples 1 to 7) disposed with recording layers respectively containing the comparative dye compounds A to G, provide high reflectance and high percentage modulation with respect to the bluish-purple semiconductor laser, and show less change in their percentage modulation even when subjected to the forced conditions. Accordingly, each of the optical discs that used the phthalocyanine derivative of the present invention had high recording characteristics with respect to a shortwave laser and high storability with respect to high temperatures and high humidity.
• a compound (I-3) was dissolved into dibutyl ether to obtain a coating solution for forming a recording layer (concentration: 1% by weight).
• the coating solution was spin-coated onto the surface a polycarbonate substrate (diameter: 120 nm; thickness: 0.6 mm) disposed with a spiral pre-groove (track pitch: 1.0 ⁇ m; groove width: 0.4 ⁇ m; groove depth: 0.15 ⁇ m) formed by injection molding, whereby the recording layer was formed (thickness (inside pre-groove): approximately 170 nm).
• a 14T-EFM signal was recorded on the optical disc of Example 18 at a linear velocity of 1.4 m/sec using a semiconductor laser having an oscillation wavelength of 780 nm. The recorded signal was played back using the same semiconductor laser, and the playback signal waveform was observed.
• a 14T-EFM signal was recorded on the same optical disc of Example 13 at a linear velocity of 1.4 m/sec using a semiconductor laser having an oscillation wavelength of 405 nm. The recorded signal was played back using the same semiconductor laser, and the playback signal waveform was observed.
• the signal recorded by the semiconductor laser having an oscillation wavelength of 780 nm was played back by a semiconductor laser having an oscillation wavelength of 405 nm, clear playback signal waveforms were observed.
• the optical information recording method and medium of the present invention solve conventional problems, exhibit excellent recording characteristics, and are stable with respect to high temperature and high humidity, and therefore are able to preserve recorded information over a long period of time.
• the optical information recording medium of the invention By using the phthalocyanine derivative as the recording material of the recording layer in the optical information recording medium of the invention, high density recording and playback of information can be effected by irradiating the medium with a laser having a short wavelength of 450 nm or less, and a generally available laser having a wavelength around 405 nm.
• the optical information recording medium of the invention has good recording and playback characteristics, such as high sensitivity, high reflectance, and high percentage modulation. According to the optical information recording medium of the present invention, it is possible to record information at a higher density than is the case with conventional CD-Rs and DVD-Rs, and it is thus possible to record a larger volume of information.
• the phthalocyanine derivative as the recording material of the recording layer, information can be recorded on and played back from the optical information recording medium of the invention by both a laser having a short wavelength of 450 nm or less and a laser having a wavelength of 750 to 850 nm used for conventional CD-Rs, without using different recording materials with different wavelengths. According to the invention, a highly versatile optical information recording medium is provided.
• optical information recording method of the invention enables information to be recorded by selectively irradiating the medium of the invention with either a laser having a wavelength of 450 nm or a laser having a wavelength of 750 to 850 nm.

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• 2002
  • 2002-06-25 EP EP02014175A patent/EP1271500A1/de not_active Withdrawn
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• 2005
  • 2005-06-14 US US11/151,356 patent/US20050233104A1/en not_active Abandoned
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